I went to this free, 24/7 hot spring, three times within 36 hours. There are several pools of varying temperatures, and it is quite well maintained even though it is free. There are lockers that cost 100 Yen. Highly recommend this onsen.
I love the hot spring, it's free not crowded with a variety of pools with different temperatures to suit everyone's needs. You also wear swim suits & change rooms are there.
It's cleaned thoroughly every morning & checked regularly.
We visited it after surfs, early morning, late at night etc. it was never very busy so was a relaxing space...